In his latest book, Aslan sends us on an intriguing journey through the history of human thinking about the divine.

For Aslan, the “compulsion to humanize the divine is hardwired in our brains.” Recent developments in cognitive theory suggest that certain religious ideas emerge from the workings of our nervous system, our innate tendency to attribute human causes to phenomena we encounter and to view other beings in the ways in which we see ourselves. Aslan adds a further hypothesis: Human beings have universally believed that they have an immaterial soul distinct from their physical bodies. It is from this built-in intuition, he suggests, rather than from our desires and fears, that religious ideas such as the existence of gods first came into being.

Moving from psychology to history, Aslan charts the development of ideas about the divine, as human beings projected their qualities — good and bad — onto the gods and their institutions upon the heavens. The religions that we invent serve to legitimatize and support the communities that we live within.

These experiments with ideas of a dehumanized God, Aslan tells us, ultimately fell on deaf ears, for “the concept of one god conflicts with our universal compulsion to humanize the divine.” (Centuries after his death, Zarathustra’s teachings were adopted by the Achaemenid Empire, but only after his severe monotheism was transformed into a seemingly more acceptable dualistic cosmology.)

Aslan then turns to trace the vicissitudes of the conception of God in Israelite religion and its offspring, Judaism and Christianity, and Islam. Aslan deftly displays some of the tensions within the Hebrew Bible/Old Testament between an older “monolatry” (the worship of one god among many) and the later monotheism that developed as the response to the vexing problem of the defeat at the hands of the Babylonians, the destruction of the Temple and the city of Jerusalem, and the subsequent exile of the Judean elite. The Babylonian Nebuchadnezzar was the rod of divine wrath; the catastrophe was punishment of a sinful people. Monotheism is theodicy.

According to Aslan, biblical monotheism, the conception of a deity who was the creator of all things yet also maintained his personal attributes and covenantal relationship with his people, was “an extraordinary development in the history of religion.”

If Christianity overturned Jewish monotheism, Islam was “a kind of doubling down on the very concept of monotheism.” But Islamic theologians did not stop with an affirmation of the oneness of God. In Aslan’s telling, the Islamic notion of “Divine Unity” necessarily led theologians and mystics to speculate that “God must be all,” that is, that there is no distinction to be made between God and creation.

Aslan is a born storyteller, and there is much to enjoy in this intelligent survey. Aslan is also eager to display his academic bona fides; a massive bibliography and endnotes (many comprised of extended extracts from other scholars) comprise nearly a third of the book.

His treatment of the Western tradition, however, may strike some readers as somewhat cursory. Aslan has little to say about the development of Judaism after the exilic period, skipping over the Second Temple period, when Judaism was profoundly shaped by its encounter with Hellenism, and the emergence of Rabbinic Judaism following the destruction of the Second Temple. Nor does he explore the development of Christian thought during the Middle Ages, the impact of the Reformation, or the emergence of liberal theology during the Enlightenment.

But Aslan’s book is not simply a historical study, but one with a trajectory in mind — the human history of God leads him to embrace pantheism as a spiritual option. He races through his treatment of Islam to get to the Sufi discovery of radical immanence, the unity of Creator and creation, “the inevitable end point of the monotheistic experiment. … God is not the creator of everything that exists. God is everything that exists.” And, if that is so, then Aslan, too, is “God made manifest.” After decades of spiritual searching and research, he has finally found … himself.

Jerome E. Copulsky’s writing has appeared in the New York Times, the Washington Post and the Atlantic.

God: A Human History
By Reza Aslan
(Random House; 298 pages; $28)